Université de Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, France (R.D.W., A.P., M.E.M, M.C., J.D., L.B., C.C., C.P-A., Y.G., D.B., V.D., N.R.F., S.C., S.D., D.D., L.P., P.P., F.B., J.R., L.L., M.H., M.H., O.B.).
INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, France (R.D.W.,A.P., M.E.M, M.C., J.D., L.B., C.C., C.P-A., Y.G., D.B., V.D., N.R.F., S.C., S.D., D.D., L.P., P.P., F.B., J.R., L.L., M.H., M.H., O.B.).
Circ Arrhythm Electrophysiol. 2018 Aug;11(8):e005913. doi: 10.1161/CIRCEP.117.005913.
Background Papillary muscles are an important source of ventricular tachycardia (VT). Yet little is known about the role of the right ventricular (RV) endocavity structure, the moderator band (MB). The aim of this study was to determine the characteristics of the MB that may predispose to arrhythmia substrates. Methods Ventricular wedge preparations with intact MBs were studied from humans (n=2) and sheep (n=15; 40-50 kg). RV endocardium was optically mapped, and electrical recordings were measured along the MB and septum. S1S2 pacing of the RV free wall, MB, or combined S1-RV S2-MB sites were assessed. Human (n=2) and sheep (n=4) MB tissue constituents were assessed histologically. Results The MB structure was remarkably organized as 2 excitable, yet uncoupled compartments of myocardium and Purkinje. In humans, action potential duration heterogeneity between MB and RV myocardium was found (324.6±12.0 versus 364.0±8.4 ms; P<0.0001). S1S2-MB pacing induced unidirectional propagation via MB myocardium, permitting sustained macroreentrant VT. In sheep, the incidence of VT for RV, MB, and S1-RV S2-MB pacing was 1.3%, 5.1%, and 10.3%. Severing the MB led to VT termination, confirming a primary arrhythmic role. Inducible preparations had shorter action potential duration in the MB than RV (259.3±45.2 versus 300.7±38.5 ms; P<0.05), whereas noninducible preparations showed no difference (312.0±30.3 versus 310.0±24.6 ms, respectively). Conclusions The MB presents anatomic and electrical compartmentalization between myocardium and Purkinje fibers, providing a substrate for macroreentry. The vulnerability to sustain VT via this mechanism is dependent on MB structure and action potential duration gradients between the RV free wall and MB.
乳头肌是室性心动过速（VT）的重要来源。然而，对于右心室（RV）心腔结构——节制索（MB）的作用知之甚少。本研究旨在确定可能导致心律失常基质的 MB 特征。
从人类（n=2）和绵羊（n=15；40-50 公斤）中研究了带有完整 MB 的心室楔形标本。对 RV 心内膜进行光学标测，并沿 MB 和室间隔测量电记录。评估 RV 游离壁、MB 或 S1-RV S2-MB 联合部位的 S1S2 起搏。对人类（n=2）和绵羊（n=4）MB 组织成分进行组织学评估。
MB 结构非常规整，由 2 个可兴奋但不耦联的心肌和浦肯野纤维组成。在人类中，发现 MB 与 RV 心肌之间的动作电位时程异质性（324.6±12.0 与 364.0±8.4 ms；P<0.0001）。S1S2-MB 起搏通过 MB 心肌引起单向传导，从而产生持续的大折返性 VT。在绵羊中，RV、MB 和 S1-RV S2-MB 起搏的 VT 发生率分别为 1.3%、5.1%和 10.3%。切断 MB 可导致 VT 终止，证实了其主要的心律失常作用。可诱导标本的 MB 动作电位时程短于 RV（259.3±45.2 与 300.7±38.5 ms；P<0.05），而不可诱导标本则无差异（312.0±30.3 与 310.0±24.6 ms）。
MB 在心肌和浦肯野纤维之间呈现出解剖和电分离，为大折返提供了基质。通过这种机制维持 VT 的易感性取决于 MB 结构和 RV 游离壁与 MB 之间的动作电位时程梯度。
